Egbert hadfield



.FFICEQ ROBERT HADFIELD, OF. SHEFFIELD, COUNTY OF YORK, ENGLAND.

STEEL.

SPECIFICATION forming part of Letters Patent No. 342,867, dated June 1,1886.

Application filed July 19, 1885. Serial No. 172,081. (Specimens)Patented in England December 4, 1881, No. 15,949.

To all whom it may concern.-

Be it known that I, ROBERT TIADFIELD, of Sheffield, in the county ofYork, England, have invented a new and useful Improvement in Steel; andI do hereby declare the following to be a full, clear, and exactdescription thereof.

My invention relates to the manufacture of a new and useful metallicalloy or admixture, the principal constituents of which are i rou(Fe)and silicon, (Si,) but which may also contain carbon, as well as otheringredients, such as sulphur and phosphorous, necessarily present in themetal, such alloy having most of the qualities peculiar to ordinarycarbon steel, besides other qualities peculiar to my improved metal. assteel, although the presence of carbon, while not injurious, isuuessential, the metal depending for its steely qualities chiefly on thepresence of a large percentage of silicon.

To enable others skilled in the art to manufacture my improved steel, Iwill proceed to describe the process which I employ, which forms thesubject-matter ofanother application for Letters Patent, Serial No.164,679, tiled May 7, 1885.

The condition of the iron which forms the basis of my improved steel,and from which it is manufactured, may be that of ordinary pigmetal,cast-iron, steel,wroughtiron, steel or iron scrap, or a mixture of allor any of these, and the process or processes by which the iron or steelis manufactured or reduced or subsequently treated is immaterial, theonly necessary requirement being that the iron before the addition ofthe silicon should be substantially decarburized, by which I mean notnecessarily devoid of carbon, but that the metal should be or shouldhave been previously decarburized wholly or to a great ex tent; hence myimproved process is applicable to the manufacture ofiron or steel bymeans of the Bessemer, open-hearth, or cruci- 5cbe present in myimproved steel, and then the desired percentage of silicon is added;

This improved metal I shall speak of while if the crucible process isemployed, the silicon addition may be introduced at any stage of theprocess.

Hitherto in the manufacture of high-class steels it has been considerednecessary to employ the best and most costly qualities of iron, and toreduce the percentage of silicon in the resulting steel to the lowestpoint practicable-say one-tenth of one per cent. or less, so aspractically to exclude silicon therefrom, as its presence in the steelhas been supposed to be injurious. I have discovered, however, that ifsilicon is present in sufficient'quantitysay one and one-half per cent.to five per cent-the resulting product is a steel of very superiorquality and possessing certain marked characteristics, and I have alsodiscovered that when this is the case the presence of sulphur andphosphorus in the iron, which forms the basis of "the process to adegree which would materially injure ordinary steel, is no disadvantagewhatever. There is, however, a practical difficulty in the production ofan alloy or mixture of silicon and iron having the desired percentage ofsilicon, arising from the fact that in the process of refining anddecarburizing the metal the silicon present is oxidized before thecarbon, so that especially in the open-hearth, p uddling, and Bessemerprocesses it has been ascertained by analysis of the metal at differentstages of treatment that the amount of carbon remains undiminished untilthe silicon has been removed below the point necessary to produce myimproved steel, so that, although a large percentage of silicon bepresent in the charge of iron under treatment, or be added theretoprevious to the process of reduction, refinement, or decarburization,the resulting metal,

even after only a partial decarburization, is

almost entirely desiliconized.

In the manufacture of my improved steel, if pig metal, cast-iron, scrap,or a mixture of these with steel or wrought-iron scrap is used as thebasis, the metal is treated in the ordinary way by the Bessemer,open-hearth, or other decarburizing and refining process or apparatusuntil the melted charge is decarburized to the desired point, more orless carbon being left in the metal, as may be desired. By this time anysilicon which waspresen in the charge before treatment will have beenpractically eliminated by oxidation, so that if the oxidizing process isarrested when the silicon is added the exact amount or percentage ofsilicon added to the charge at that point of the process will be easilydetermined, the amount of silicon present in the silicon addition beingpreviously ascertained, and will be present in the resulting steel atthe close of the operation. The silicon is introduced into the wholly orsufficiently decarburized metal substantiall y in the same manner asspiegeleisen is commonly added as a final step in the process of makingsteel by the Bessemer steelmaking process. This is done by the use ofsilicon pig-iron, hereinafter referred to as silicon addition (awell-known product of the blast-furnace process) or other ferro-silicon,which is incorporated with the charge, as above stated, either in asolid or melted condition. The gross amount of silicon pig orferro-silicon to be added will depend on the amount of silicon which itcontains, which will be ascertained beforehand, and also of course onthe percentage of silicon which the resulting steel is desired tocontain. I prefer to use as the silicon addition silicon cast-iron orsilicon pigiron containing from eight to ten per cent. of silicon, forthe reason that such material is low in carbon, and, being a specialproduct, is more uniform in its quality and constituents.

As an example of manufacture, I add to two thousand pounds ofdecarburized and desiliconized iron six hundred and fifty pounds of thesilicon pigiron herein referred to; also, if necessary, a sufficientquantity of ferro manganese, but usually the silicon pig containssufficient manganese'withoutrequiring a separate addition thereof. It isdesirable to keep the carbon under one per cent. in those steelscontaining two and a half per cent. of silicon and upward on account ofthe difficulty which would be experienced in working the ingots whensuch percentage of carbon is exceeded.

here it is desired that the resulting product should have greatertoughness, I introduce such amount of the silicouizing addition as willyield a steel having from one and a half to two per cent. of silicon,and where greater hardness is required I increase the amount of siliconin varying proportions up to about five per cent. After the siliconaddition is incorporated with the charge, it is ready to be run intoingots or other forms, as may be desired.

If my improved steel is to be made by the crucible process, the basis ofthe operation or prime charge being wrought-iron or steel scrap, or bothcombined, the process is then conducted in the usual way, the amount ofcarbon. if any is used, being preferably less than in the ordinarysteel-making operation, and the siliconizing addition is introduced intothe crucible at any stage of the process and becomes thoroughlyincorporated with the charge.

Manganese may be added to the steel made by my process in the usualway.

M'y improved steel thus manufactured possesses after tempering peculiarhardness, (depending in degree, as before stated, on the amount ofsilicon which it contains,) so that it is specially adapted for what isknown as tool steel purposes, edge-tools, &c. It has also other peculiarand valuablecharacteristics, among which I would mention that it hasgreat toughness compared with the tool steel now used. It is morewaxyand malleable in working when heated than high-carbon steel, and istherefore more readily shaped under the hammer, and when cold is moreeasily cut and tooled than ordinary steel. It is not so brittle asordinary steel, and is less liable to be burned in heating, and to whatis known as water-cracking. It is also susceptible of hardeningand'tempering by the same methods and with substantially the same effectas can bon steel.

I desire it to be understood that in the foregoing specification andfollowing claim I use the word steel to designate a metal of which ironis the basis, irrespective of the amount of carbon which it may contain,and having the well-known characteristics of hardening and temperingpossessed by carbon steel.

I am aware that cast or pig irons high in silicon are well known in thearts; but these do not possess the properties described as belonging tomy improved product, such as malleability and the susceptibility tohardening and tempering; nor does my improved product contain carbon inas high a percentage nor in as great a ratio to silicon as is usuallyfound in these silicons, pigs, or cast-irons. As one example of thecomposition of my improved product, I give the following analysis, notconfining myself, however, to these proportions: Specimen No.408-carbon, 0.78; silicon, 2.4.9; sulphur, .09; phosphorus, .07;manganese, .64. This analysis plainly indicates the difference betweenmy improved product and cast or pig irons high in silicon. I thereforedo not claim such cast or pig irons.

Having thus described my improved steel and the method of producingsame, what I claim as my invention, and desire to secure by LettersPatent, is-

As a new article of manufacture, steel or a malleable silicious compoundof iron containing silicon in the proportion of from one and one-halfper cent. to five per cent. of silicon.

In testimony whereof I have hereunto set my hand this 15th day of July,A. D. 1885.

ROBERT IIADFIELD.

Witnesses:

R. A. HADFIELD, WILLIAM CROWLEY.

ICC

